1. Field of the Invention
The present invention relates to a method of manufacturing a head gimbal assembly for use in a magnetic disk drive, the head gimbal assembly including a slider and a suspension that supports the slider.
2. Description of the Related Art
A magnetic disk drive incorporates a head gimbal assembly including a slider and a suspension that supports the slider. The slider incorporates a magnetic head element. The magnetic head element includes a magnetoresistive element (hereinafter referred to as MR element) for reading, and an induction-type electromagnetic transducer for writing.
The suspension is attached to a driving arm of an actuator intended for moving the slider in a direction across the tracks of a recording medium. The slider has a medium facing surface that faces a magnetic disk as the recording medium. The slider is held by the suspension and slightly flies over the surface of the recording medium by means of an airflow that passes between the medium facing surface and the recording medium.
The suspension has a plurality of leads for electrically connecting the magnetic head element in the slider to a control circuit that controls the magnetic head element. On the outer surface of the slider, there are provided a plurality of electrode pads that are electrically connected to the magnetic head element. Each of the plurality of leads includes a slender lead body and a terminal. The terminal is provided at one end of the lead body and is electrically and physically connected to a corresponding electrode pad. The other end of the lead body is electrically connected to the control circuit.
Conventional methods for electrically and physically connecting the electrode pads of the slider and the terminals of the leads to each other mainly include the following first and second methods. A first method is disclosed in, for example, U.S. Pat. No. 5,828,031 and U.S. Patent Application Publication No. 2006/0139809 A1. In the method, the electrode pads and the terminals are arranged orthogonal to each other with solder balls interposed therebetween. The solder balls are irradiated with a laser beam so that the solder balls melt to form solder fillets, whereby the electrode pads and the terminals are connected to each other.
A second method is disclosed in, for example, U.S. Pat. No. 6,321,974 B1. In the method, the terminals of the leads are pressed against the electrode pads of the slider and ultrasonic vibrations are applied to the terminals by the top part of an ultrasonic vibrator, whereby the electrode pads and the terminals are ultrasonic-bonded to each other.
JP-A-2007-12169 describes a method of fixing the slider to the suspension such that the slider is easily detachable from the suspension for the purpose of conducting a test to evaluate the flying characteristics of the slider and the characteristics of the magnetic head element. In this method, the terminals of the leads have spring characteristics. The slider is positioned by a stopper that is disposed on a side opposite to the terminals of the leads, and the terminals of the leads are pressed against terminals of the slider. This electrically connects the terminals of the leads and the terminals of the slider to each other, and fixes the slider to the suspension. JP-A-2007-12169 describes that if the test result is satisfactory, conductor balls of solder or gold are interposed between the terminals of the leads and the terminals of the slider, and the conductor balls are then melted by irradiation with laser light, whereby the terminals of the leads and the terminals of the slider are electrically and physically connected to each other.
With the recent miniaturization of sliders, the electrode pads of the sliders have become accordingly smaller in size and in spacing. For improved performance of magnetic disk drives, not only the MR element and the induction-type electromagnetic transducer but also one or more other elements may in the future be provided in a slider. Examples of such other elements include a heater for controlling the distance between the medium facing surface and the recording medium, a temperature sensor, and a laser diode for use in heat-assisted magnetic recording. The increase of elements provided in a slider entails an increase in the number of electrode pads of the slider. This makes the electrode pads of the slider even smaller in size and in spacing.
If the electrode pads of the slider are small in size and in spacing as mentioned above, the conventional methods for electrically and physically connecting the electrode pads of the slider and the terminals of the leads to each other have the following problems.
The first conventional method requires solder balls of considerable size in order to allow the formation of the solder fillets. Therefore, according to this method, the melted solder can widely flow out from between the electrode pads and the terminals, so that adjoining electrode pads and adjoining terminals may be electrically connected to each other by the solder. The first method thus has the problem of poor reliability of connection between a plurality of pairs of electrode pads and terminals.
With the second conventional method, it is difficult to bond a plurality of pairs of electrode pads and terminals uniformly if a large-sized ultrasonic vibrator is used to ultrasonic-bond the plurality of pairs of electrode pads and terminals at the same time. The second method therefore has the problem of poor reliability of connection between a plurality of pairs of electrode pads and terminals. The second method also has a problem in that the ultrasonic vibrator is difficult to miniaturize in line with the miniaturization of the electrode pads.